“What kind of key opens a haunted house?”/“A spoo-key.”

A popular Halloween haunted house riddle is:
 
Q: What kind of key opens the door of a haunted house?
A: A spoo-key.
 
The joke was included in the book Holiday Howlers: Jokes for Punny Parties (2004).
 
“How do you unlock a haunted house?”/“With a skeleton key” is a similar riddle.
     
 
Google Books
Holiday Howlers:
Jokes for Punny Parties
By Peter Roop and Connie Roop
Pictures by Brian Gable
Minneapolis, MN: Carolrhoda Books
2004
Pg. 14:
Q: How does a ghost open the door of a haunted house?
A: She uses a spoo-key.
 
Straight Dope Message Board
Am I missing something with this Laffy Taffy joke?
Marlitharn
09-30-2007, 07:48 AM
Actually, they have “How do you unlock a haunted house? With a spoo-key!”. Which isn’t as painful as “What kind of car does a ghost drive? A boo-ick!” but it comes close.
 
Twitter
Aaron Newcomer
‏@937aaron
@circasurvive what kind of key opens a haunted house?  a spookey
3:32 PM - 29 Oct 2009
 
Twitter
The Real Mish M.
‏@elektra88
Only 24 kids in 2 hours so far.  Bored.  Reading Laffy Taff:  What kind of key opens a haunted house?  A spoo-key!
9:57 PM - 31 Oct 2009
   
Facebook
Angie Rivera Lippy
‎to JuWanna the Clown
October 6, 2014 ·
Halloween jokes!!! :O)
(...)
Q. What key opens a Haunted House?
A. A spooKEY!
 
Google Books
The House on Spooky Street
By Laurie S. Sutton
North Mankato, MN: Stone Arch Books
2015
Pg. 108:
How did Scooby-Doo escape the haunted house?
a. He played on the run-down piano until he found the right key!
b. He unlocked the door with a spoo-key!
 
Twitter
Jule’s Lifestyle Co.
‏@juleslifestylec
What kind of key opens a haunted house? .... a spooKEY #HappyHalloween
4:15 PM - 31 Oct 2016